public class Test {
    private static Math math;

    public static void main(String[] args) {
        double sum = 0;
        int j = 1;
        for (int i = 1; i <= 100; i++) {

            sum += j*(1.0/i);
            j = - j;
        }
        System.out.println(sum);
    }
}//计算1/1-1/2+1/3-1/4+1/5 …… + 1/99 - 1/100 的值。
